HIP-4 Part 1: Add a Curve connector for Ethereum to Gateway

[james-hummingbot]

Before submitting this PR, please make sure:

• Your code builds clean without any errors or warnings
• You are using approved title ("feat/", "fix/", "docs/", "refactor/")

A description of the changes proposed in the pull request:

• Vendorize the curve-js library and make changes necessary in order for it to work with Infura and gateway
• Create the curve connector and make it usable via the amm routes
• Add a condition to hummingbot that assumes Curve allowances are infinite. curve-js handles allowances internally when it performs trades.

Tests performed by the developer:

Tips for QA testing:

Curve can only be tested on the mainnet. You can test with WETH and USDT or any pairs that you see here (excluding ETH): https://curve.fi/pools

[james-hummingbot]

Snapshot: https://snapshot.org/#/hbot-prp.eth/proposal/0xc4b33028d3762755b195cc9e6fe0cce8c13a806f3481023a39698929c9107b77
HIP-4: https://snapshot.org/#/hbot-ip.eth/proposal/0x0f86d963fc90c972efb78f6ae56b2ae2b189c6d6c8ffa1470aa000251a1163cb

[james-hummingbot]

@JeremyKono I will test on polygon then notify you guys.

[JeremyKono]

Hi @james-hummingbot, what's the update on this PR?

[james-hummingbot]

@JeremyKono I'll try to have it ready this week.

[james-hummingbot]

@Faouzijedidi1 @cardosofede Have you guys seen these errors before?

[james-hummingbot]

@Faouzijedidi1 @cardosofede
Specifically these errors: Cannot find module @uniswap. Not sure what causes that.
I will fix the curve related ones.

[james-hummingbot]

I need to increase the code coverage

[james-hummingbot]

@Faouzijedidi1 @cardosofede
Hey guys, I sort of forgot about this. Do think this is something the community cares about much?

[fengtality]

Hummingbot Foundation is opening up this bounty for pickup by a qualified community developer. There is 200K HBOT reserved for this bounty.

Original dev @james-hummingbot says that maintaining this connector requires keeping the curvejs fork up to date which is required because they hardcode some settings, so it requires a maintainer willing to keep it updated. James can give them a few pointers.

Interested devs should DM their qualifications (XP with JS and blockchain dev) to me.

[fengtality]

Gateway is now in a standalone repo, so the dev that picks up the Curve bounty should create a PR on that repo: https://github.com/hummingbot/gateway